How can I find a v2 cluster/node to debug the v2 protocol flow?

[newshellcode]

I have successfully compiled the Dev Tunnels SDK. However, when attempting to test the v2 node selection algorithms, all available service regions I tried only return v1 nodes.How can I locate or connect to a v2 cluster so that I can properly debug the v2 protocol flow?

[plequere-ms]

Apologies, I'm not sure what you mean by "debugging the v2 protocol flow." Also, there is no such thing as "v2 clusters". We have made recent changes to our API to pave the way for new fallback scenarios and support multiple clusters per region, but from a client's standpoint, a cluster is a cluster. There's nothing that distinguishes the new clusters that we're building out from the original ones.

[newshellcode]

Thanks for the clarification on clusters.

Let me re-ask using the SDK's own terminology. In the C# SDK, TunnelRelayConection defines two host websocket subprotocols:

HostWebSocketSubProtocol = "tunnel-relay-host"
HostWebSocketSubProtocolV2 = "tunnel-relay-host-v2-dev" (with the comment "The '-dev' suffix will be dropped when the v2 protocol is stable")
When a host connects, the client offers a list of subprotocols and the relay selects one during the websocket upgrade. My question is specifically about that selection:

When I have a host offer only tunnel-relay-host-v2-dev, every relay endpoint I've tried rejects it and the upgrade fals back to tunnel-relay-host (v1). Is tunnel-relay-host-v2-dev currently accepted by the relay for host connections anywhere, or is it still server-side gated / not yet enabled for third-party hosts?

The reason I ask: the v2 host path uses an encrypted outer SSH channel and the session-reconnect@microsoft.com extension, whereas the v1 host path runs the outer SSH unencrypted, so the reconnect handshake can't be exercised. I'm trying to test that path against a real relay. If v2 host isn't available yet, is there a timeline or a flag to opt in?

For reference, when offering only the v2 host subprotocol the upgrade fails with the relay selecting tunel-relay-host instead — I never see tunnel-relay-host-v2-dev come back as the negotiated subprotocol on any endpoint.